BRUSSELS EU leaders told Russia to stop bombing Western-backed opposition fighters in Syria and accused Moscow and Iran of threatening peace efforts, as well as helping Islamic State and worsening refugee flows in Europe.

Leaders made the call a week after major powers agreed a pause in combat in Syria, where Russia has focused on attacking rebels opposed to its ally President Bashar al-Assad, and urged that the "cessation of hostilities" be respected.

"The European Council calls on the Syrian regime and its allies to stop at once attacking non-terrorist opposition groups, which threatens the prospects for peace, benefits Da'esh and drives the refugee crisis," EU leaders said in a joint statement following a summit, referring to Islamic State.

Russian and Iranian military involvement in Syria's six-year civil war is reinvigorating the Syrian government's fightback, bringing swift gains for Assad in recent weeks and putting full encirclement of the rebel stronghold of Aleppo, a major symbol of the uprising, within sight.

"A nationwide cessation of hostilities must urgently be implemented," leaders said. They said the pause in fighting should apply to "any party currently engaged in military or paramilitary hostilities" that was not designated a terrorist group by the United Nations Security Council.

EU leaders also condemned the bombing of Syrian towns and called for an end to bombing in civilian areas near Aleppo and Syria's border with Turkey. Missiles hit five medical centres and two schools in rebel-held Syrian towns this week, the United Nations and residents said.

The attacks came as Russian-backed Syrian troops intensified their push towards Aleppo.

(Reporting by Robin Emmott)

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